sharp, 77mm filter, IS + 2.8, great colors, contrast, the built quality is not so bad

Cons:

no hood and need special order

It was difficult to decide which lens to get. I was narrowing it down to 3 lenses 16-35 F2.8, 17-40 F4 and the 17-55 F2.8. I decided to go for the 17-55 F2.8 because of image stableliser and extra rich 55mm. This was more important to me than the weather sealing and the way it was built. I dont need a strong lens as Im not breaking nuts!!! The F2.8 + image stabaliser means 3 stops down from F 2.8 to F1.4. In general I am happy with the lens including the way its built (after reading reviews about it being poorly built and that it was very fragile). I believe it has a strong construction. 77mm filter size suits most of the lenses and dont need only 1 size filter.

After using the lens for more than 1 1/2 years in freezing conditions in Romania and high humidiy in Malayasian jungle to the very dry and dusty south Australia I have no dust on the lens (might be luck or a good made product). I have used filters all the time from first minute of use.

Concluding I am pleased with the lens and in the future it may get some dust but wont affect the image quality as its not in the focus, but would recommend it if you are looking for a fast lens with no weather sealing then this is the one for you.

Canon perhaps should make all lenses as standard dust sealed and weather sealed.

Overall I have got good results and very little post processing in Photoshop.